1. Field of the Invention
The present invention relates generally to a locking apparatus for a shift lever in an automatic transmission and, more particularly, to a locking apparatus comprised to lock a shift lever against rotation in a particular non-driving position on the basis of a predetermined condition.
2. Description of the Related Art
In general, with respect to a vehicle which is equipped with an automatic transmission, a parking brake is applied and a shift lever is shifted to a "P" position for securing the vehicle in a firmly braked state during parking, and an occupant leaves the vehicle thereafter. When an engine of the vehicle is started at a "P" position of the shift lever and the shift lever is shifted to a "D" position to run the vehicle, the shift lever always passes through an "R" position at an intermediate point. Accordingly, it is desirable that a foot brake be applied until the shift lever is moved from the "P" position to the "D" position.
The above-described operation of the shift lever and other operations are carried out relative to each other, and it has been considered that if such an associated operation of brake application is not achieved, the shift lever is kept locked in the "P" position so as not to be capable of shifting to any other position.
For instance, Japanese Utility Model Laid-open No. 20343/1987 proposes an arrangement that a shift lever is inhibited against rotation when a foot brake is not operative.
In the arrangement disclosed in the above-described Japanese Utility Model Laid-open No. 20343/1987, there is a problem that if any electrical trouble occurs, the shift lever cannot be released from its locked state.
Japanese Utility Model Laid-open No. 176253/1984 discloses a manual lever apparatus in which a locked state of a shift lever can be manually released even if electricity is not being supplied to a solenoid adapted to restrict movement of the shift lever. This apparatus is arranged such that a plunger pin which is driven by the solenoid directly contacts a detent pin which serves to hold the shift lever in a parking position, and the shift lever is restricted against movement. In this apparatus, there can be problems where the portion of the plunger pin that contacts the detent pin is scratched, and the plunger pin can not be smoothly drawn into the solenoid.